Write a formula representing the following function. Use k as the proportionality constant.

The strength, S, of a beam is proportional to the cube of its thickness, h.

S(h) = ?

I'm not even 100% sure what this problem means. Can someone direct me towards how I'm suppose to solve this?

This problem is deceptive in its simplicity:

Something that is proportional to another thing simply means that the two things will have a constant ratio. The k is the proportionality constant because its magnitude determines this ratio. If they had a ratio of 1:1, k would = 1, such that the strength of the beam is exactly the same as its cube of thickness. If it was 0.5, the strength would be half of its cube of thickness...and so on.